Can I rotate the viewport exactly by 180 degrees in the y-axis?

Let’s say that I have cube like this:

Pressing num7 shows [5]. But what if I want to see the opposite side [6], in the perfect angle as [5]? Is there any way to rotate the viewport by 180 degrees in the y-axis? If the viewport is rotated by the x-axis, the opposite face becomes upside-down and therefore [9].

Numpad1 -> Front
CTRL + Numpad1 -> Back

And the same goes to Left/Right, Top/Botttom

Thanks. But I wrote the question wrongly. What I wanted to know was [5] and the y-axis. I had been wondering about this and suddenly remembered it and wrote the question, but asked about the wrong face.

If I press num7, it shows [5]. I want to rotate the viewport horizontally (that is, by the vertical y-axis) by 180 degrees to see the opposite side. In the texture, I wrote “6” up-side-down, so, if [1] becomes [3] by rotating, [5] should become [9]. But if I press Ctrl+num7 or num9, it rotates in the x-axis and becomes [6]. I want to see [9]. Is that possible?

There isn’t any shortcut for that, and the ‘view_axis’ operator doesn’t have that functionality.
It’s possible to write a new operator for that and assign it to new shortcut…
The operator should set the view_matrix to Matrix([[-1.0,0.0,0.0,0.0],[0.0,-1.0,0.0,0.0],[0.0,0.0,-1.0,0.0], [0.0,0.0,0.0,1.0]]).

You can roll the viewport with Shift+Numpad 4 and 6. Hitting one of those 12 times will roll the view 180 degrees (12 x 15 degrees which is the rotation angle defined in preferences under Navigation>Orbit & Pan(

would be nice if someone can write a new small addon in N panel may be to rotate around any viewport axis and any angles !

thanks
happy bl